Encoder, decoder, encoding method, and decoding method

Abstract

An encoder includes: circuitry; and memory coupled to the circuitry. The circuitry, in operation, stores a first parameter into a bitstream, the first parameter indicating, as a prediction mode, one of (i) a multiple prediction mode in which a prediction image is generated by overlapping an inter prediction image of a current block and an intra prediction image of the current block and (ii) one of a plurality of prediction modes including a non-rectangular mode in which a prediction image is generated for each non-rectangular partition in the current block, and encodes the current block according to the prediction mode.

1 . An encoding method for encoding a video, comprising:
 obtaining a current block from a coding tree unit (CTU);   storing a first parameter into a bitstream, the first parameter indicating, as a prediction mode, one of (i) a multiple prediction mode in which a prediction image is generated by overlapping an inter prediction image of the current block and an intra prediction image of the current block and (ii) one of a plurality of prediction modes including a non-rectangular mode in which a prediction image is generated for each non-rectangular partition in the current block; and   encoding the current block according to the prediction mode, wherein encoding the current block using the multiple prediction mode and encoding the current block using the non-rectangular mode are mutually exclusive.   
     
     
         2 . A decoding method for decoding a video, comprising:
 obtaining a current block from a coding tree unit (CTU);   parsing a first parameter from a bitstream, the first parameter indicating, as a prediction mode, one of (i) a multiple prediction mode in which a prediction image is generated by overlapping an inter prediction image of the current block and an intra prediction image of the current block and (ii) one of a plurality of prediction modes including a non-rectangular mode in which a prediction image is generated for each non-rectangular partition in the current block; and   decoding the current block according to the prediction mode, wherein decoding the current block using the multiple prediction mode and decoding the current block using the non-rectangular mode are mutually exclusive.